Orthodontic screw-type implant

ABSTRACT

The invention relates to an orthodontic screw implant comprising an elongated body, which has a thread for anchoring in a jaw bone and carries a polygon head having on an end face two slots which cross in a recess which has a diameter that is at least twice the width of the slots.

The invention relates to an orthodontic screw implant comprising an elongated body, which has a thread for anchoring in a jaw bone and carries a polygon head having on an end face two slots which cross in a recess.

Such screw implants have a head with a cross-shaped recess to which can be anchored an apparatus for a dental misalignment correction. An archwire that can exert pressure for the teeth misalignment correction is placed in the cross recession. Customarily, the archwire is additionally guided by one or more brackets that are bonded to the teeth.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an orthodontic screw implant that facilitates the treatment of teeth misalignments both for patients and orthodontist.

This object is attained by a screw implant with the features set forth in claim 1. Other advantageous embodiments are the object of dependent claims.

The central recess of a screw implant according to the invention avoids sharp edges in the crossing slots. Thus, a wire can be bent with a larger bending radius which requires less force for insertion in the crossing slots, thus facilitating the orthodontist's job. Further, within the scope of the invention it was found that, because of the preventing of a sharp kink, considerable less pressure is placed on the wire. The use of a screw implant according to the invention for the inserting of a bent wire in the slots crossing in the recess, particularly bent at a 90° angle, has therefore a positive effect on the lasting durability of the wire.

In order to remove the sharp edges of crossing slots a central milling can be effectuated, for example, which results in a cylindrical recess from which extend the four partial slots. Between the partial slots are convex bent lateral faces of the recess.

Preferably, the slots have a width that is less than two thirds, especially preferable one half or less, of the distance between the opposite lateral faces of the recess. In such a manner, it is possible to attain that a wire in the cross-shaped recess can be bent with a greater radius, therefore being under less stress. Thus, the danger of a breaking wire is reduced.

Preferably, the recess has a diameter of at least 1 mm. The width of the slots is preferably 0.45 mm to 0.6 mm, especially 0.5 mm to 0.6 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further details and advantages with reference to an embodiment shown in the accompanying drawings, wherein

FIG. 1 shows greatly enlarged a lateral view of an orthodontic screw implant

FIG. 2 shows the same anchor screw in a lateral view, rotated 90° with respect to FIG. 1

FIG. 3 shows the cross-section A-A through the screw according to FIG. 1, and

FIG. 4 shows a top view of the head of the anchor screw according to FIG. 1

DETAILED DESCRIPTION

FIGS. 1 to 4 illustrate the embodiment of an anchor screw of an orthodontic screw implant. The anchor screw has an elongated body with a thread 10 for the anchoring into a jaw bone, provided with two crossing slots 3 on an end face intended to protrude from the jaw bone. The slots are made for the inserting of an archwire. The end face with the crossing-slots 3 is arranged on a head 1 of the anchor screw, which head is configured as a hexagon 2 for the gripping of a wrench. Other embodiments that enable a torque transmission by means of a positive locking are also possible such as, e.g., an octagon, generally an outer polygon.

As illustrated in FIG. 4, the slots 3, which have a width of 0.55 mm, cross in a cylindrical recess 21 having lateral faces 22 extending in a longitudinal direction of the body that are broken by the slots 3. The recess 21 can be formed by milling the center of the cross-shaped slot 3. FIG. 4 illustrates the recess 21 with an archwire 23 inserted in the cross-shaped recess. The lateral faces 22 of the recess 21 are at a distance from the curvature of the archwire 23 so that the archwire 23 is under the least possible stress.

The center of the recess 21 coincides with the center of the crossing slots.

The head 1 is provided with an external annular groove 5 underneath the cap 4. By virtue of the annular groove 5 and the cross-shaped slot 3 an orthopedic apparatus can be anchored at the head of the anchor screw by means of a wire. The recess 21 can extend throughout the cap 4. It is also possible that the cross-shaped recess 3 is drilled beneath the cap.

A collar 6 is adjacent to the outer hexagon 2 serving as limit stop for a wrench. A smooth conic section 7 is attached to the collar 7, which section changes to a smooth cylindrical shank 8. Anther conic section 9 is attached to the shank 8 that becomes a threaded part 10 which ends in a tip 11.

With exception of its tip 11, the threaded part 10 has a constant core diameter D along its entire length. Around the core 12 winds a single-flight, self-grooving thread, whose flanks 13 or thread troughs 15 have an asymmetrical profile. Alternatively, a multiple thread can also be used. In each turn 14 after the point 11, in the troughs 15 between each two flanks 13 is formed a cutting edge 16 on a radial plane. The radial plane comprises the longitudinal axis 19 of the anchor screw and is in FIG. 1 vertical on the drawing plane while in the illustration of FIG. 2 it coincides with the drawing plane. The cutting edge 16 is an edge of a recess that is delimited by an area 17 that is part of a cylinder barrel surface, the axis 20 of which is at a distance of the longitudinal axis 19 of the anchor screw and is delimited by a plane end face 18 that is oriented at a right angle to the cylinder barrel surface 17. Alternatively, the end face 18 can also deviate by a slight positive or negative angle, preferably not more than ±10° from the right-angled orientation. All cutting edges are on a common plane and do not transverse the flanks 13. However, the cutting edges can also be on different planes.

REFERENCE NUMBERS LIST

-   1 Head -   2 Outer hexagon -   3 Cross-shaped slot -   4 Cap -   5 Annular groove -   6 Collar -   7 Section -   8 Shank -   9 Section -   10 Threaded part -   11 Tip -   12 Core -   13 Flanks -   14 Thread -   15 Thread trough -   16 Cutting edge -   17 Cylinder jacket area -   18 End face -   19 Longitudinal axis -   20 Axis of 17 -   21 Recess -   22 Lateral faces -   23 Archwire 

1. An orthodontic screw implant comprising an elongated body, which has a thread for anchoring in a jaw bone and carries a polygon head having on an end face two slots which cross in a recess which has a diameter that is at least twice the width of the slots.
 2. A screw implant according to claim 1, wherein the diameter of the recess is at least 1 mm.
 3. A screw implant according to claim 1, wherein the recess is cylindrical.
 4. A screw implant according to claim 1, wherein the recess has a center that coincides with the center of the cross-shaped slots.
 5. A screw implant according to claim 1, wherein the width of the slots is 0.45 mm to 0.6 mm.
 6. A screw implant according to claim 1, wherein the width of the slots is 0.5 mm to 0.6 mm.
 7. A screw implant according to claim 1, wherein the recess is milled.
 8. A screw implant according to claim 1, wherein the thread has a self-grooving or self-cutting profile.
 9. A screw implant according to claim 1, wherein the head has a larger width than the threaded body.
 10. A screw implant according to claim 1, wherein the head has a polygonal or hexagonal cross-section.
 11. A screw implant according to claim 1, wherein between the end face and the thread is provided a threadless cylindrical or conical shank.
 12. A screw implant according to claim 1, wherein an annular groove is provided in the head for the insertion of an archwire.
 13. A screw implant according to claim 1 with a wire bent at 90° arranged in the slots crossing in the recess. 